基于血管阻断剂放大肿瘤内MMP9信号的高分子纳米药物研究

Tumor high expression proteinase sensitive nanomedicines, hold great potential to selectively release drugs to tumor. And it exhibited advantage to reduce drug side-effect and prolong circulation, becoming the recent research focus. While this kind of nanodrugs has limitation in therapeutic effect and universality, as differences among tumor locations, individuals, cancer stages make the proteinase expression significantly different. As to this question, in this proposal, vascular disrupting agent-induced neoplastic matrix metalloproteinase 9 (MMP9) upregulation was applied to develop a novel strategy and increase the selective release of nanodrugs. Poly-L-glutamine grafted polyethyl glycol polymer carrier was employed to bond combretastatin A-4 (CA4) or/and MMP9 selective substrate peptide modified doxorubicin (MMP9sp-Dox). CA4 recruits TIE2+ expressed macrophage (TEM) to tumor, and TEM highly expresses MMP9, amplifying neoplastic MMP9 signal. MMP9sp-Dox part recognize this signal, selectively releasing drugs to tumor. This may significantly improve the safety and therapeutic efficacy of nanomedicines. Polymer grafted CA4 inducing neoplastic MMP9 overexpression, Doxorubicin nanodrug accumulating in tumor, tumor selectively releasing, anti-tumor mechanism and efficacy will be investigated in this study.

肿瘤高表达蛋白酶敏感的纳米药物，具有肿瘤内选择性释放药物的潜力，其在改善抗肿瘤药物毒副作用、血液稳定性等方面展现了优势，是近年的研究热点。但肿瘤部位、个体、病程阶段不同，蛋白酶表达差异显著，这使此类纳米药物的有效性和普适性受到了限制。针对这一问题，本课题基于血管阻断剂放大瘤内基质金属蛋白酶（MMP9）信号，提出了提升纳米药物选择性释放的新策略：以聚谷氨酸接枝聚乙二醇聚合物为载体，键合康普瑞汀A-4（CA4）或/和MMP9底物肽-阿霉素（MMP9sp-Dox）；CA4召集表达TIE2+的巨噬细胞（TEM）到肿瘤，TEM大量表达MMP9，放大瘤内MMP9信号，MMP9sp-Dox部分对这一信号识别，从而选择性地在肿瘤内释放药物，该策略有望提高纳米药物的安全性和疗效。本课题将对CA4高分子键合药致瘤内MMP9高表达、阿霉素纳米药物的肿瘤富集、肿瘤内选择性释放、作用机制、治疗效果进行考察和评价。

肿瘤微环境酶敏感纳米药物持续、有效地抑制肿瘤生长具有很好的应用前景。然而，肿瘤与正常组织中目标酶的差异往往不尽人意，限制了酶敏感性药物的疗效。如何在快速抑制肿瘤的同时增强目标酶的表达，提高药物的肿瘤选择性释放仍具有挑战性。本课题提出了以康普瑞汀A4纳米药物（CA4-NPs）放大瘤内MMP9信号，增加MMP9激活的MMP9底物肽连接的阿霉素前药纳米药物（MMP9-Dox-NPs）的肿瘤选择性释放策略。CA4-NPs利用高分子键合方法制备，MMP9-Dox-NPs是两亲性高分子材料亲疏水担载MMP9-Dox得到的。结果表明，CA4-NPs使4T1肿瘤模型上瘤内MMP9的表达提高了约5.6倍，而正常组织无明显差异。相应地，组织分布结果表明CA4-NPs使MMP9-Dox-NPs的肿瘤选择性释放提高了约3.7倍，而对正常组织无影响。由于CA4-NPs导致MMP9信号放大并促进了小分子阿霉素在瘤内的分布，最终CA4-NPs与MMP9-Dox-NPs在MMP9高表达4T1肿瘤和MMP9低表达C26肿瘤上均产生了协同的抗癌疗效，说明该策略具有普适性意义。进而，这个策略为基于肿瘤选择性释放的抗肿瘤治疗提供了新思路。